1. Field of the Invention
The invention relates to a backlight module, more particularly to a backlight module having a light emitting diode (LED) as a light source.
2. Description of the Related Art
Referring to FIGS. 1 and 2, there are usually two types of backlight modules, i.e., a side-edge type of backlight module, as shown in FIG. 1, and a direct type of backlight module, as shown in FIG. 2. Since a relatively long distance is required for mixing lights emitted from LEDs 1 to obtain mixed light having even brightness and color, a light box 11 of a conventional backlight module cannot be reduced in thickness advantageously.
Although the distance for mixing the lights emitted from the LEDs 1 can be reduced by decreasing distances among the LEDs 1, in this way, the number of the LEDs 1 is increased, which in turn results in higher production costs, and aggravates the problem of heat dissipation. Additionally, a specific lens (not shown) can be used to improve the light mixing effect. However, the design for the lens is difficult, and the production cost thereof is relatively high. Furthermore, the light mixing effect achievable by the lens is limited when the arrangement density of the LEDs 1 used in the backlight module is small.
U.S. Pat. No. 6,726,341 discloses a storage compartment equipped with a light emitting diode (LED), in which a rigid rod is required as a light guide for guiding light emitted by the LED. U.S. Pat. No. 6,742,907 discloses a liquid crystal display device in which a light guide plate is required for guiding light illuminated from a point light source.
In the conventional backlight module as shown in FIG. 2, the LEDs 1 are usually installed in the light box 11. It is required to disassemble the light box 11 when broken LEDs 1 are to be replaced with new ones.